1. Field of the Invention
The present invention relates to a centralized control system for terminal devices capable of controlling an image forming apparatus such as a copying machine, facsimile, and laser beam printer, and further to a terminal devices such as an automatic vendor with the use of communication lines from a remote place.
2. Description of the Related Art
An image forming apparatus such as a copying machine requires maintenance and inspection including replacement of photoreceptors and toner so as to remain in good condition. A specialized service company is in charge of these management of the apparatus, together with management of rental fee for the apparatus. The service company sends a service person regularly or in the case where the copying machine is out of order. However, an increase in the number of copying machines with the spreading use thereof, and also an increase in the number of inspection items with the copying machine becoming more multi-functional will lead to an increasing burden on the service company. In view of this, there exists a growing need for a labor-saving system capable of centrally and remotely controlling a plurality of the copying machines by a central unit.
These circumstances are similar to those for an automatic vendor, such as the one for drinks or cigarettes. A specialized vendor company is in charge of sales management and maintenance and inspection for the automatic vendor. Accordingly, there exists a growing need for a system capable of centrally and remotely controlling a plurality of automatic vendors by a central unit.
A system for management of a plurality of copying machines is disclosed in U.S. Pat. No. 4,583,834. In the disclosed system, various operating data of the copying machine, such as a total number of copies, machine malfunctions and amounts of remaining copy sheets and toner, are transmitted to a computer through a communication network. The computer processes the transmitted data and feeds back to the copying machine instructions.
A centralized control system in which data of copying machines are transmitted from respective data terminal devices to a central unit through a communication network is proposed by the inventors. In this proposed system, communication between each data terminal device and the central unit is achieved at a fixed transmission time.
Nevertheless, in the proposed centralized control system as described above, in the case where the central unit is unable to receive the information at the fixed transmission time due to abnormality in the data terminal device, abnormality in connection of the communication line or the like, the central unit is incapable of confirming that it has been unable to receive the information. As a result, such a problem will arise that the abnormality in the data terminal device or in the connection of the communication line cannot be detected at an early stage.
Further, in the case where the proposed centralized control system as described above is adopted for controlling the copying machine, the following problem may arise. Since the power supply for the data terminal device is generally fed from the copying machine, in the case where the power supply for the data terminal device is shut off because the copying machine is not in use at the fixed transmission time, the data terminal device cannot transmit the data at the fixed transmission time.
Especially, in recent years, in the case where copying operations are not executed over a predetermined period of time, most types of copying machines have the power supply thereof automatically shut off to save the power. Accordingly, there is a likelihood that the above problem may frequently arise. These circumstances are also similar to those for the automatic vendor. Especially, since nighttime sales of alcoholic beverages by the use of the automatic vendor is frequently regulated by an ordinance, the power supply for the automatic vendor is often shut off at night.
Accordingly, in the proposed centralized control system, in the case where the information to be transmitted at the fixed transmission time is not transmitted to the central unit, the central unit cannot collect the necessary data with certainty. As a result, such a problem may arise that the controlling function of the central unit may not be fully utilized.